The Bangkok Tree House hotel pushes the boundaries of eco-friendliness and still offers a stylish welcome. Click on the magnifying glass for a larger version of the image

You couldn't pull up in front of the Bangkok Tree House hotel in a swanky car even if you wanted to. Not only does it not really have a "front", it doesn't even have road access. But if flash cars were your thing, you probably wouldn't want to stay here anyway, for the Bangkok Tree House seems to have decided to see how far it can push eco-friendliness and still offer a stylish welcome.

A bit of green awareness doesn't go amiss in traffic-choked Bangkok. I fight my way to the Tree House through the city's seemingly permanent rot dtit (traffic jam). Leaving my taxi at Sanphawut Pier, a few miles from the centre (to be really green you could walk the mile or so from Bangna Skytrain station), I board a ferry full of schoolchildren, young commuters and old folk with shopping bags and cross the wide grey Chao Phraya river into a different world.

Or perhaps a different century. Phra Pradaeng is a pear-shaped patch of land cut off by a meander in the Chao Phraya where, I'm told, life goes on much as it did 200 years ago. Factory chimneys and high-rises are visible across the river but here all is semi-natural swampland, fruit plantations and fishermen's houses on stilts.

Tong, a smiling young Thai from the hotel, meets me at the ferry. Walking past orchards of papaya and coconut, within five minutes we come to a set of small bamboo, steel and glass units. These are the rooms, linked by a raised wooden walkway to the restaurant and pool. One "room" has no walls or ceiling and guests sleep under the stars.

Wood and steel cubes make up the Bangkok Tree House

I am disorientated when first shown to my three-storey "nest". The floor of the (doorless) loo is clear glass – giving a view of primordial mud and lush vegetation six feet below. I get my jet-lagged head around that and see that the shower is, oh, out there on the wooden balcony we've just walked past (it's only later I spot the thick bamboo blind). Eventually I make it up a steep (space-saving) alternate-tread staircase to the bedroom, and then up steep outdoor steps to the sundeck.

After a snooze on the huge and inviting bed, I can see that, provided you are nimble on your pins and not scared of heights, this is a perfect blend of stylish and environment-friendly. The bed's on a blond wood platform (the only part of the nest with aircon). The sundeck has a lounger for two and views of treetops and shipping. Fittings are of pleasing chunky wood, towels feel robust rather than fluffy.

The hotel is the brainchild of 36-year-old Jirayu (Joey) Tulyanond, whose mother owns the delightful 10-room Old Bangkok Inn, in town. Though a Bangkok native, Joey hadn't heard of Phra Pradaeng until Time Magazine named it Asia's best urban oasis in 2006. Seeing the potential of this antidote to the car-clogged city, he put notes through doors across the peninsula asking if any land was likely to be for sale. Phra Pradaeng is green belt land, with no factories or major development, but Joey's 12-room boutique hotel, when he found a patch of land handy for the Skytrain, was small enough to count as a homestay.

Coconut for breakfast. Photograph: Liz Boulter

I sleep soundly in my bamboo eyrie, and at breakfast Joey starts my education in green but gorgeous hospitality. Sumalee, who works in the kitchen, takes a machete and leads us to a row of palms just outside. Choosing a ripe coconut, she detaches it from the tree and hacks away the green husk and the top of the shell to reveal an interior brimming with sweet juice. When I've gorged on this, plus tea, toast, eggs and seven types of tropical fruit, Joey and I climb on bikes and set off into Phra Pradaeng. From 2013, any guest who arrives by bike gets a 15% discount, and use of a bike maintenance workshop.

As we ride, he lists his hotel's green credentials: floors, walls and ceilings of reclaimed wood and local bamboo, insulated with old juice cartons; LED lighting powered by solar and wind energy; solar cookers in the organic meat-free kitchen; rainwater harvesting; and local sourcing of products not grown on site.

I only take in so much of this, because the cycling, while fun, takes concentration. We're riding on elevated concrete walkways, passing simple wooden houses and banana, papaya and mango orchards. The pace of life is slow: the village headman nods as he passes on his moped, and when we reach a road, there's just one tuktuk in sight. A 250-year-old temple in Bang Namphueng Nok, where we stop for coffee, is mouldering away quietly, precious wall paintings unregarded in the gloom.

An open-air 'bedroom' at the hotel

Tourists do find their way to Phra Pradaeng – there is a popular floating market here at weekends, but with nowhere to stay, visitors always piled back into town afterwards. That is changing with, as well as the Tree House, a few cheap, atmospheric guesthouses, such as Phuengnang Homestay (+66 2461 38101, phuengnanghome.com, doubles from about £20). But Joey's place is really cleaning up – literally. Sharing a river with 10 million people means plenty of rubbish finds its way downstream. The Tree House has pledged to remove a kilo of trash from the Chao Phraya for every booking it takes: as of last Novemberit had cleared 1,021kg.

One eccentric feature is naming the rooms after insects. As justification, Joey likes to quote Jonas Salk, developer of the polio vaccine: "If all the insects were to disappear from the earth, within 50 years all life on earth would end. If all human beings disappeared from the earth, within 50 years all forms of life would flourish." My room, with butterflies everywhere, is great, but there is one with giant ants …

So my list of people the Tree House would not suit includes – along with petrolheads, families with toddlers, and anyone with vertigo – those with an aversion to creepy-crawlies. The elderly or disabled might struggle, too. But that still leaves an awful lot of us for whom this is an ideal Bangkok bolthole – as friendly to the planet as it is to its guests.

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